or a policy or politics was a protest against apartheid. >> reporter: as a senator obama had visited mandela, and the president and mrs. obama brought their doubters to robben island prison so they could better understand what mandela had suffered. after he died, michelle obama tweeted we will forever draw strength and inspiration from nelson mandela's extraordinary example of moral courage, kindness and humility. bill clinton tweeted a picture and wrote, "i will never forget my friend madibaa," use the affectionate name by which mandela was known to his followers. mandela wasn't always on the u.s. side. in the 1980s president reagan supported apartheid regime, and eastern as protests broke out an college campuses across america demanding the u.s. punish the regime. ♪ ♪ free mandela >> reporter: "free nelson mandela" became a popular anthem for black and white americans. finally, congress, including key republicans, overrode reagan's veto imposing the economic sanctions that helped break the apartheid regime. that set the stage for mandela's triumphant visit to washington as his country'